Temperature indicator for optical module

ABSTRACT

An optical module includes a housing with a first end and a handle extending from the second end. A temperature indicator on the handle is thermally coupled to the housing to improve correlation with an optical module surface temperature. The temperature indicator provides an indication that the optical module surface temperature of the housing exceeds a predefined temperature limit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/919,832, filed Jul. 2, 2020, the entirety of which are herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to optical modules, and moreparticularly, to identifying a safe touch surface temperature on theoptical module.

BACKGROUND

Over the past several years, there has been a tremendous increase in theneed for higher performance communications networks. Increasedperformance requirements have led to an increase in energy use resultingin greater heat dissipation from components. As power dissipationincreases, cooling of components is becoming very difficult. The surfacetemperature of removable components such as optical modules installed ina network device may reach temperatures that are unsafe for human touch.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a perspective of an optical module with a temperatureindicator strip inserted into a line card, in accordance with oneembodiment.

FIG. 1B is a front view of the optical module and line card.

FIG. 2A is a perspective of the optical module of FIG. 1A.

FIG. 2B is a front view of the optical module of FIG. 2A.

FIG. 3 illustrates changes in temperature of the optical module.

FIG. 4A is a perspective of an optical module with a temperatureindicator handle indicating a safe touch temperature, in accordance withone embodiment.

FIG. 4B is a perspective of the optical module of FIG. 4A with thetemperature indicator handle indicating a temperature exceeding a safetouch temperature limit.

FIG. 5A is a front view of the optical module of FIG. 4A.

FIG. 5B is a front view of the optical module of FIG. 4B.

FIG. 6A is a front view of a line card with a plurality of opticalmodules installed with the temperature indicator handles indicating asafe touch temperature.

FIG. 6B is a front view of the line card and optical modules of FIG. 6Awith the temperature indicator handles indicating a temperatureexceeding the safe touch temperature limit.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

In one embodiment, an apparatus generally comprises an optical modulecomprising a first end for insertion into a network device and a secondend extending from the network device when the optical module isinserted into the network device and a temperature indicator thermallycoupled to the optical module and extending from the second end of theoptical module. The temperature indicator provides an indication that asurface temperature of the optical module exceeds a predefined safetouch temperature limit.

In another embodiment, an apparatus generally comprises a line cardcomprising a plurality of optical module ports and a plurality ofoptical modules inserted into the optical module ports, each of theoptical modules comprising a temperature indicator thermally coupled toa housing of the optical module. The temperature indicator provides anindication that a surface temperature of the optical module exceeds apredefined safe touch temperature limit and is viewable with the opticalmodule inserted into the line card.

In yet another embodiment, an apparatus comprises an optical modulecomprising a first end for electrically coupling the optical module to anetwork device and a second end comprising an optical connector, and atemperature indicator strip thermally coupled to the optical module andextending from the second end of the optical module. The temperatureindicator strip is configured to change between a first color indicatingthat a surface temperature of the optical module is below a predefinedsafe touch temperature limit and a second color indicating that thesurface temperature of the optical module exceeds the predefined safetouch temperature limit.

Further understanding of the features and advantages of the embodimentsdescribed herein may be realized by reference to the remaining portionsof the specification and the attached drawings.

Example Embodiments

The following description is presented to enable one of ordinary skillin the art to make and use the embodiments. Descriptions of specificembodiments and applications are provided only as examples, and variousmodifications will be readily apparent to those skilled in the art. Thegeneral principles described herein may be applied to other applicationswithout departing from the scope of the embodiments. Thus, theembodiments are not to be limited to those shown, but are to be accordedthe widest scope consistent with the principles and features describedherein. For purpose of clarity, details relating to technical materialthat is known in the technical fields related to the embodiments havenot been described in detail.

As performance requirements increase, optical modules continue toincrease in speed and power. As optical power dissipation increases,cooling of optical components is becoming very difficult. For example,pluggable optical modules (transceivers) have limited heat sink surfaceavailability and use of a riding heatsink is not very effective in termsof heat conduction between surfaces. Due to the high power dissipationand limited cooling, optical modules operate at high temperatures,resulting in hot external metal surfaces. The surface temperature of theoptical module may reach temperatures that are unsafe for human touch.Heat conduction within a metal shell of the optical module body mayresult in the optical module reaching high temperatures, including aportion of the module that is outside of the chassis, which may reachtemperatures above 55° C. and even up to 75° C. or higher. A safe touchsurface temperature to protect maintenance personnel may be limited to48° C. for example, however, this limit is often exceeded duringoperation due to cooling limitations. The problem is further compoundedby the optical density on line cards, fabric cards, and routeprocessor/controller cards. Since there is little room to work, atechnician may hold onto whatever he can reach to remove the module. Inaddition to a risk of burn injury, there is also a risk of damage oreven possibly fire when a hot module is removed and placed on a surfacethat is not safe for exposure to high temperatures. Therefore, it isimportant for the technician to be able to easily identify if theoptical module is safe to touch to avoid burn injuries or other damage.

The embodiments described herein provide a temperature indicatorintegrated into an optical module to indicate when a surface of theoptical module exceeds a safe touch temperature (i.e., too hot to safelytouch) and when it is safe to touch and remove the module. Thetemperature indicator allows maintenance personnel to easily identifywhen an external surface of the optical module is below a safe touchtemperature limit so that the user knows when it is safe to remove theoptical module without risk of burn injury. The embodiments describedherein may provide compliance with any number of safety standards andprevent burn injury due to accidental touch, thereby providing animproved user experience.

It is to be understood that the term “optical module” as used hereinrefers to any modular optical component (e.g., optical transceivermodule) configured for insertion and removal from a modular electronicsystem (network device), which may include insertion and removal from aline card. The term “line card” as used herein refers to any type ofcard (e.g., line card, fabric card, service card, route processor card,controller card, or other card) that may be installed in the networkdevice. Also, it is to be understood that the terms front, rear, above,or below as may be used herein are only relative terms and that thenetwork device may have ports for receiving the optical modules locatedon any face. For example, the term “front face” as used herein refers toan exposed or accessible side of the network device in which ports arelocated.

Referring now to the drawings, and first to FIGS. 1A and 1B, aperspective and front view of an optical module 10 with a temperatureindicator (temperature indicator strip, temperature indicator tab) 12 isshown in accordance with one embodiment inserted into an optical moduleport 11 in line card 14. In one or more embodiments, an apparatuscomprises the optical module 10 comprising a first end for insertioninto the network device (e.g., line card 14 of network device) and asecond end extending from the network device when the optical module isinserted into the network device, and the temperature indicator 12thermally coupled to the optical module (e.g., thermally coupled to ahousing of the optical module) and extending from the second end of theoptical module. As described in detail below, the temperature indicator12 is configured to sense a surface temperature of the optical modulethrough thermal conduction between an optical module housing and thetemperature indicator and provide an indication that the surfacetemperature of the optical module exceeds a predefined safe touchtemperature limit. The temperature limit may be selected based on moduletype or environment, or may be based on a standard (e.g., NEBS GR63touch safe temperature limit of 48° C., UL 60950 touch safe temperaturelimit of 60° C., or any other standard).

The optical module 10 may be a pluggable transceiver module in any formfactor (e.g., SFP (Small Form-Factor Pluggable), QSFP (Quad SmallForm-Factor Pluggable), QSFP-DD, CFP (C Form-Factor Pluggable), CFP2,CXP (100G/Common Transceiver Pluggable), and the like) operable within anetwork device (e.g., line card 14). The optical module 10 may, forexample, be plugged into a module based switch, router, or other opticalplatform port. A cable 16 connected to the optical module 10 at anoptical connector 17 (FIG. 1B) may carry, for example, data (e.g., fiberoptics, optical array, fabric) or data and power. The opticaltransceiver module 10 operates as an engine that bidirectionallyconverts optical signals to electrical signals or in general as aninterface to a network element copper wire or optical fiber. A host forthe pluggable optical module 10 may include the line card 14 comprisinga printed circuit board (PCB) 15 and electronic components and circuitsoperable to interface telecommunications lines in a telecommunicationsnetwork. The host may be configured to perform one or more operationsand receive any number or type of pluggable transceiver modules 10configured for transmitting and receiving signals.

In the example shown in FIGS. 1A and 1B, the optical module 10 comprisesa pull-release handle (pull tab) 19. While the handle 19 may assist withinsertion or removal of the optical module 10, removal of the opticalmodule typically involves grabbing onto an end of a case (housing) 24 ofthe optical module extending from the line card (FIG. 1A). In theexample shown in FIGS. 1A and 1B, the temperature indicator strip 12 islocated generally within (or adjacent to) an opening defined by thehandle 19 of the optical module 10 and may extend above the handle foreasy viewing of the temperature indicator strip. The temperatureindicator strip 12 may be customized for different types of moduleswithout any changes to existing handle designs. The temperatureindicator strip 12 may be thermally connected (embedded) within (or on)the optical module surface (external surface of housing 24) to provideimproved correlation with the optical module surface temperature. Thetemperature indicator strip 12 extends outward from the second end ofthe optical module housing 24 so that it is easily visible to indicateif the outer surface of the module is safe to touch or too hot to touch(i.e., exceeds safe human touch operating temperature as suggested byregulatory compliance standards or other specified temperature limit).This helps to prevent burn injury to a technician (operator, maintenancepersonnel, user) and lets the technician known when it is safe to removethe optical module 10 from the network device during OIR (OnlineInsertion and Removal).

In one or more embodiments, a change in the optical module surfacetemperature is identified by a change in color of the temperatureindicator 12. For example, as described below, the temperature indicatorstrip 12 may comprise a thermochromic (also referred to asthermochromatic) pigment (substance, compound) (or other temperaturechanging material) configured to change from a first color to a secondcolor at the predefined safe touch temperature limit and return to thefirst color when the surface temperature of the optical module fallsbelow the predefined safe touch temperature limit (reversable colorchanging properties).

It is to be understood that the line card 14 shown in FIGS. 1A and 1Band the optical module 10 inserted therein is only an example and theline card (e.g., line card, fabric card, route processor card,controller card, and the like) may include any number of ports 11 forreceiving any number or type of optical modules in any arrangement.

FIG. 2A is a perspective and FIG. 2B is a front view of the opticalmodule 10 removed from the line card. The optical module 10 comprises afirst end 20 for insertion into a network device (e.g., line card of amodular electronic system) and a second end 22 extending from thenetwork device when the optical module is inserted into the networkdevice (as shown in FIG. 1A). The first end 20 of the optical module 10defines an electrical interface and the second end defines an opticalinterface between the optical module and one or more optical fibers. Thefirst end 20 of the optical module 10 comprises an electrical connector(e.g., multiple contact edge type connector) for electrically couplingthe optical module 10 to the network device (e.g., through opticalmodule cage interface at the PCB 15) and the second end 22 of theoptical module comprises one or more of the optical connectors 17 (e.g.,MPO (Multi-fibre Push On) connector or LC duplex connector) (FIGS. 1A,2A, and 2B). The optical module housing 24 may conform to industrystandards packaging dimensions and may be formed from any suitablematerial.

As previously noted, the optical module 10 may include the pull-releasehandle (pull tab) 19, which may assist with insertion or removal of theoptical module 10. As shown in FIG. 2A, the handle 19 may be generallyU-shaped and extend outward from a front face (second end 22) of theoptical module housing 24. The handle 19 may also be used to operate alatch mechanism to release the optical module 10. As shown in FIGS. 2Aand 2B, the temperature indicator strip 12 may be positioned to extendoutward from the second end 22 of the optical module 10 and at leastpartially above the handle 19 so that it is easily viewable from a frontend of the optical module (FIG. 2B). The temperature indicator strip 12is secured (coupled) to the optical module housing (case) 24 andtherefore provides a close approximation as to the surface temperatureof the optical module housing.

FIG. 3 illustrates color changes in the temperature indicator strip 12as the optical module surface temperature increases (as viewed from leftto right in FIG. 3). The temperature indicator strip 12 may comprise,for example, a rubber (or other flexible material) strip with one ormore thermochromic pigments. The temperature indicator 12 is configuredto change color when a temperature of the thermochromic pigment deviatesfrom a predetermined or calibrated temperature threshold. Thethermochromic pigments may be customized for different color schemes andactivation temperatures, which are calibrated with the optical modulesurface temperature. The temperature indicator strip 12 is thermallycoupled to the module surface to provide correlation with the opticalmodule surface temperature.

In one embodiment, the thermochromic pigment is capable of undergoing afirst thermochromic change from a first state (first color) to a secondstate (second color). For example, the temperature indicator strip 12may be configured to change between a first color indicating that asurface temperature of the optical module is below a predefined safetouch temperature limit and a second color indicating that the surfacetemperature of the optical module exceeds the predefined safe touchtemperature limit. In the example shown in FIG. 3, the temperatureindicator 12 comprises more than one thermochromic pigment or compound,each sensitive to a different temperature limit so that the temperatureindicator is capable of changing between at least three colors, each ofthe colors indicating a different temperature range. For example, ayellow color may indicate that the optical module surface temperature isbelow a first predefined temperature limit and is safe to touch. A pinkcolor may indicate that the optical module surface temperature is abovethe first predefined limit but below a second predefined limit toindicate that the optical module is cooling but may still be too hot forsafe touch. A purple color may indicate that the optical module surfacetemperature is above the second predefined limit and should not betouched. It is to be understood that any color schemes may be used andthe colors and number of color changes used may be different thandescribed herein.

It is to be understood that the shape and size of the temperatureindicator strip 12 may be different than shown herein without departingfrom the scope of the embodiments. In one example, the strip 12 maygenerally correspond in size and shape to an opening defined by thehandle 19 and vary according to the size of the optical module andhandle. The temperature indicator strip 12 may be designed to correspondto different types of handle (pull tab) designs, without impacting theaccessibility of the module front side port or requiring any designchange to the handle.

FIGS. 4A and 4B are perspectives and FIGS. 5A and 5B are front viewsillustrating another example of an optical module 40 with a temperatureindicator (temperature indicator handle) 42, in accordance with oneembodiment. As previously described, the handle 42 extends outward fromthe second end of the optical module and is positioned above cables 46.In one or more embodiments, a portion of the handle 42 is made withthermochromic pigments impregnated into a base thermoplastic resinmaterial (or other suitable thermally conductive material) forming thehandle (or a portion of the handle). In the example shown in FIGS.4A-5B, a reference color is added to a first portion 44 a of the handle42 for comparison with a second portion 44 b containing the temperaturesensitive thermochromic material. The first portion 44 a displays areference color that remains unchanged and the second portion 44 bdisplays a color that changes based on the surface temperature of theoptical module 40. In one example, the second portion 44 b may changefrom blue (cold) to yellow (hot). In one example, when the color on thetwo portions 44 a, 44 b of the temperature indicator handle 42 aredifferent (FIGS. 4A and 5A), the optical module has cooled and is safeto remove. When the color on the two portions 44 a, 44 b matches (FIGS.4B and 5B), the optical module 40 is hot and not safe to remove, therebyindicating that the user should wait until the second portion 44 bchanges to a different color than the first portion 44 a. The change incolor is easily viewable from a front end of the optical moduleextending from the network device as shown in FIGS. 5A and 5B. In one ormore embodiments, the optical module 40 may include a tag (sticker,label) on the exposed end with a key identifying cold and hot colorpatterns of the temperature indicator handle 42.

FIGS. 6A and 6B illustrate an implementations on a line card 60comprising a plurality of optical module ports 61 for receiving aplurality of optical modules 40 (e.g., CFP2 form factor) and 62 (e.g.,QSFP form factor). FIG. 6A is a front view of the line card 60 andoptical modules 40, 62 that have cooled and are safe to remove (colorson each portion 44 a, 44 b of the temperature indicator handle 42 aredifferent). FIG. 6B is a front view of the line card 60 and opticalmodules 40, 62 when the optical modules are hot (exceed safe touchtemperature limit) (colors on each portion 44 a, 44 b of the temperatureindicator handle matches). As shown in FIGS. 6A and 6B the temperatureindicator is always visible, even in high port density systems.

It is to be understood that the colors and use of a reference color, orwhether the colors match when the optical module surface is hot, asdescribed above is only an example and other colors or configurationsmay be used without departing from the scope of the embodiments. Also,the optical modules 40, 62 may cool at different rates based on alocation within the network device, module type, or operatingconditions. Thus, one or more of the optical modules 40, 62 shown inFIGS. 6A and 6B may be sufficiently cooled (safe to remove) while one ormore of the optical modules are still hot (unsafe to remove).

In another example, a liquid crystal layer or label may be placed on thetemperature indicator (strip 12, handle 42, or exposed metal surface ofthe optical module housing 24 as shown in FIG. 1A). The liquid crystalchanges color in response to heat, thereby creating a visual indicationof the temperature of the outer surface of the optical module. A labelmade of microencapsulated thermochromic liquid crystals (TLC) may beused to display module surface temperature. The crystals are sensitiveto temperature and change their position/twist so as to affect theabsorbed and reflected light. A backlit hot surface caution label mayalso be used (e.g., positioned on handle, temperature indicator strip,or exposed portion of housing). The caution symbol may be added on topof encapsulated TLC film to highlight the hot surface symbol only whenthe temperature exceeds the safe touch temperature limit. In thisexample, the hot surface symbol is illuminated only after thetemperature exceeds a specified threshold value. The label is reversibleand becomes dark when the module surface cools down.

The embodiments described herein may operate in the context of a datacommunications network including multiple network devices. The networkmay include any number of network devices in communication via anynumber of nodes (e.g., routers, switches, gateways, controllers, edgedevices, access devices, aggregation devices, core nodes, intermediatenodes, or other network devices), which facilitate passage of data overone or more networks. One or more of the network devices may compriseone or more optical modules with the temperature indicator describedherein. The network device may include one or more processor, memory,and network interfaces, with one or more of these components located ona line card removably inserted into the network device. The networkdevices may communicate over or be in communication with one or morenetworks, which may include any number or arrangement of networkcommunications devices (e.g., switches, access points, routers, or otherdevices) operable to route (switch, forward) data communications.

Although the method and apparatus have been described in accordance withthe embodiments shown, one of ordinary skill in the art will readilyrecognize that there could be variations made without departing from thescope of the embodiments. Accordingly, it is intended that all mattercontained in the above description and shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. An apparatus comprising: an optical module with ahousing comprising a first end and a second end; a handle extending fromthe second end of the housing of the optical module; and a temperatureindicator on the handle, wherein the temperature indicator is thermallycoupled to the housing to improve correlation with an optical modulesurface temperature, wherein the temperature indicator provides anindication that the optical module surface temperature of the housingexceeds a predefined temperature limit.
 2. The apparatus of claim 1,wherein the indication is based on a comparison of a first color of thetemperature indicator on the handle to a second color on the second endof the optical module.
 3. The apparatus of claim 1, wherein theindication is based on a comparison of a first color of the temperatureindicator on the handle to a reference color displayed on the handle. 4.The apparatus of claim 1, wherein the indication comprises a change incolor.
 5. The apparatus of claim 4, further comprising a reference labelidentifying the change in color between a first color indicating theoptical module surface temperature is cooler than the predefinedtemperature limit and a second color indicating the optical modulesurface temperature is hotter than the predefined temperature limit. 6.The apparatus of claim 1, wherein the temperature indicator comprises athermochromic pigment configured to change from a first color to asecond color at said predefined temperature limit and return to saidfirst color when the optical module surface temperature falls below saidpredefined temperature limit.
 7. The apparatus of claim 1, wherein thetemperature indicator comprises a first portion displaying a referencecolor that remains unchanged and a second portion displaying a colorthat changes based on the optical module surface temperature.
 8. Theapparatus of claim 1, wherein the temperature indicator is operable tochange between at least three colors, each color of the at least threecolors indicating a different temperature range.
 9. The apparatus ofclaim 1, wherein the temperature indicator is positioned on the handleto be visible while the optical module is inserted into a networkdevice.
 10. The apparatus of claim 1, wherein the handle comprises arelease handle that is configured to operate a latch mechanism.
 11. Asystem comprising: a line card comprising a plurality of optical moduleports; and a plurality of optical modules inserted into the plurality ofoptical module ports, the plurality of optical modules including a firstoptical module comprising a temperature indicator on a handle of thefirst optical module, wherein the temperature indicator is thermallycoupled to a housing of the first optical module to improve correlationwith a surface temperature of the first optical module, wherein thetemperature indicator provides an indication that the surfacetemperature of the first optical module exceeds a predefined temperaturelimit and the temperature indicator is viewable with the first opticalmodule inserted into the line card.
 12. The system of claim 11, whereinthe indication is based on a comparison of a first color of thetemperature indicator on the handle to a second color on the housing ofthe first optical module.
 13. The system of claim 11, wherein theindication is based on a comparison of a first color of the temperatureindicator on the handle to a reference color displayed on the handle.14. The system of claim 11, wherein the indication comprises a change incolor.
 15. The system of claim 14, further comprising a reference labelidentifying the change in color between a first color indicating thesurface temperature of the first optical module is cooler than thepredefined temperature limit and a second color indicating the surfacetemperature of the first optical module is hotter than the predefinedtemperature limit.
 16. The system of claim 11, wherein the temperatureindicator is operable to change between at least three colors, eachcolor of the at least three colors indicating a different temperaturerange.
 17. The system of claim 11, wherein the handle comprises arelease handle that is configured to operate a latch mechanism releasingthe first optical module from the line card.
 18. An apparatuscomprising: an optical module comprising a first end for electricallycoupling the optical module to a network device and a second endcomprising an optical connector; and a temperature indicator strip on ahandle extending from the second end, the temperature indicator stripthermally coupled to the optical module to improve correlation with asurface temperature of the optical module, wherein the temperatureindicator strip is configured to change between a first color indicatingthat the surface temperature of the optical module is below a predefinedtemperature limit and a second color indicating that the surfacetemperature exceeds the predefined temperature limit.
 19. The apparatusof claim 18, further comprising a reference label on the second end ofthe optical module displaying the first color.
 20. The apparatus ofclaim 18, wherein the temperature indicator strip comprises a firstportion displaying the first color that remains unchanged and a secondportion that changes between the first color and the second color basedon the surface temperature of the optical module.